Work will continue on the structure and function of plant and bacterial toxins. The modified toxins have been prepared and their potential use as cancer therapeutic agents will be studied. The molecular basis of the toxic action of the toxin in vivo will also be investigated. Studies are continuing on NAD transfer enzyme including NADases to ascertain whether their mechanisms of action are similar to those of bacterial toxins involving ADPR moiety of NAD. Covalently bound known chemotherapeutic drugs to peptides are being prepared and their effects in vivo and on cell culture lines are being investigated. Work is continuing on high frequency magnetic resonance studies of natural and analog nucleotides to ascertain their exact structure. The mechanism of binding of these substances to various proteins are now under investigation. Metabolic characteristics of human tumors growing in the athymic mouse are being investigated. BIBLIOGRAPHIC REFERENCES: B.R. Venter, J.C. Venter and N.O. Kaplan. Affinity Isolation of Cultured Tumor Cells Utilizing Drugs and Hormones Covalently Bound to Glass and Sepharose Beads. Proc. Nat. Acad. Sci. U.S.A. 73, 2013 (1976). N.O. Kaplan. Target Directed Cancer Chemotherapeutical Agents in Proc. Eighth Miami Winter Symposia on Cancer Enzymology, 12-16 January 1976, Miami, Florida. Academic Press, N.Y. (1976).